Snow returns to Pilsen

So far the temperature is around 0 °C so it melts rapidly. But that should change during the following days. For Tuesday, the temperature is forecast to go to -12 °C. Brrr.

Do you have deja vu? Yes, see 2007.

Barack Obama and climate change

Few challenges facing America — and the world — are more urgent than combating climate change. The science is beyond dispute and the facts are clear. Sea levels are rising. Coastlines are shrinking. We’ve seen record drought, spreading famine, and storms that are growing stronger with each passing hurricane season.

Well, indeed. Quite a few challenges are more urgent than climate change: pretty much all of them. The science is, by definition, never beyond dispute. But it is true that some facts are established pretty well. They just seem to disagree with Mr Obama's statements.

For example, the sea levels continue to be rising by 2-3 millimeters a year, about 10 times slower than how they were (naturally) rising between 15,000 and 8,000 years ago. Coastlines are generally not shrinking and those that are changing are more affected by geological processes, erosion, and by the local human activity than by the climate.

We haven't seen record droughts. The famines generally seem to belong to the history as the national economies grow stronger. The 2008 Atlantic hurricane season was 1.5 times stronger than the 2006 and 2007 seasons but it was still 1.5 times weaker than the 2005 season. Sometimes things go up, sometimes they go down. There seem to be no statistically significant trends in the hurricane activity. Even theoretically, it is very unclear what the sign of such a hypothetical trend should be.

Climate change and our dependence on foreign oil, if left unaddressed, will continue to weaken our economy and threaten our national security.

Climate change cannot continue to do something if it hasn't yet started to do it. The dependence of countries on foreign oil is a function of objective circumstances, especially their own reserves relatively to other countries' reserves.

These geographical facts are usually pretty much constant as a function of time, so they cannot contribute to any weakening or strengthening of economies. The economies and trade patterns adapt to whatever external conditions they face. Moreover, as a commenter points out, the dependence is always mutual.

The dependence of a country on other countries may pose a threat to its security and independence but this threat is never infinite and a sensible politician should never try to pay an infinite price for changing the situation. Incidentally, the oil price dropped below $50 today, near 1/3 of the peak price from July 2008. Chances are for a drop towards $30. These are the developments about oil that actually matter.

I know many of you are working to confront this challenge. In particular, I want to commend Governor Sebelius, Governor Doyle, Governor Crist, Governor Blagojevich and your host, Governor Schwarzenegger – all of you have shown true leadership in the fight to combat global warming. And we’ve also seen a number of businesses doing their part by investing in clean energy technologies.

Indeed, many kinds of people and institutions are deeply immersed in this rubbish. I want to commend Václav Klaus, James Inhofe - who was reelected into his office, and others.

But too often, Washington has failed to show the same kind of leadership. That will change when I take office. My presidency will mark a new chapter in America’s leadership on climate change that will strengthen our security and create millions of new jobs in the process.

America should be ready to a new, somewhat unprecedented global situation in which it will stand on the political left side from the rest of the world and no one will be interested in its extreme policies. In the Asia-Pacific region and Europe, the support for all kinds of climate regulation is evaporating rapidly these days.

Germany is pretty much joining Italy and the Eastern Europe in rejecting any specific post-Kyoto regulations and other regions seem to follow a similar evolution. The Czech prime minister - who will probably take over the EU since January 2009 - announced today that he will reject proposals that would increase energy prices. He also opposes a "brutal" introduction of carbon indulgence markets that would be useless because other countries will ignore it.

That will start with a federal cap and trade system. We will establish strong annual targets that set us on a course to reduce emissions to their 1990 levels by 2020 and reduce them an additional 80% by 2050.

God bless America. If new economically viable alternatives emerge, there won't be any need to dictate such reductions. On the other hand, if they won't, such regulations will mean a decrease of the GDP that will be qualitatively comparable to those 80% because under normal circumstances, the inflation-adjusted GDP growth and the CO2 emission growth don't differ by more than 1-2% a year.

Further, we will invest $15 billion each year to catalyze private sector efforts to build a clean energy future. We will invest in solar power, wind power, and next generation biofuels. We will tap nuclear power, while making sure it’s safe. And we will develop clean coal technologies.

"Next generation biofuels" is a bizarre term that reflects a wishful thinking rather than existing and usable new technologies. Solar and wind power are ludicrous fads. By the way, the production of solar panels causes a huge amount of the greenhouse effect (via NF3 used for cleaning).

"Making sure that nuclear energy is safe" is just a different way of saying that President Obama might be open to the sentiments of anti-nuclear critics who may bury any conceivable future nuclear development of the U.S. at the time when nuclear energy is the only known, economically viable alternative to the fossil fuels.

This investment will not only help us reduce our dependence on foreign oil, making the United States more secure. And it will not only help us bring about a clean energy future, saving our planet. It will also help us transform our industries and steer our country out of this economic crisis by generating five million new green jobs that pay well and can’t be outsourced.

Well, they can be surely paid from the increasing U.S. debt if the country decides to pay millions of parasites who pretend to be doing useful work. But such a hot air economy will collapse soon or later.

The green jobs clearly don't bring any profit to the citizens that would make them voluntarily pay trillions of dollars. The only way how these millions of jobs can exist is that the people will be forced to pay them, either directly (for useless expensive "services" replacing the good old - but banned - energy sector) or indirectly by ballooning green budgets.

But the truth is, the United States cannot meet this challenge alone. Solving this problem will require all of us working together. I understand that your meeting is being attended by government officials from over a dozen countries, including the UK, Canada and Mexico, Brazil and Chile, Poland and Australia, India and Indonesia. And I look forward to working with all nations to meet this challenge in the coming years.

Don't expect any smooth sailing. The inclusion of Poland that critically depends on coal and that simply won't give it up is very entertaining but the other nations will oppose similar dictates, too, as soon as they realize that the projects to regulate the economies are becoming real rather than abstract nonsense used to bash America - which is what they have been so far.

Let me also say a special word to the delegates from around the world who will gather at Poland next month: your work is vital to the planet. While I won’t be President at the time of your meeting and while the United States has only one President at a time, I’ve asked Members of Congress who are attending the conference as observers to report back to me on what they learn there.

I am still not sure whether I will attend this conference in Poland, as some of the plans envisioned, because I should probably start to prepare a powerful talk in the case of Yes. ;-)

And once I take office, you can be sure that the United States will once again engage vigorously in these negotiations, and help lead the world toward a new era of global cooperation on climate change.

You should primarily check e.g. that the intelligence services will protect your life against the people in the Middle East who think that you are a Muslim traitor who has to be executed according to the rules of Islam. For ordinary infidels, the execution is optional. ;-) Also, the transition period is an ideal time for a possible new terrorist attack. See Al Qaeda's al-Zawahiri's brand new 10-minute speech dedicated to Obama's victory.

Now is the time to confront this challenge once and for all. Delay is no longer an option. Denial is no longer an acceptable response. The stakes are too high. The consequences, too serious.

Well, delay and "denial" are not only options but they're the preferred ones, at least in democratic Europe.

Stopping climate change won’t be easy. It won’t happen overnight. But I promise you this: When I am President, any governor who’s willing to promote clean energy will have a partner in the White House. Any company that’s willing to invest in clean energy will have an ally in Washington. And any nation that’s willing to join the cause of combating climate change will have an ally in the United States of America. Thank you.

Stopping climate change will be hard, indeed. You may practice - try to first stop the Earth's rotation. It's very nice to promise special advantages to companies who are going to support your ideology and politics - this approach to the state-corporation relations is usually called corruption - but be ready that not everyone will be happy to join this movement, and even for those who will join, you will not have enough resources to show all these trucklers how good an ally you are because America, its economy, and its comparative advantages are finite.

Tommaso Dorigo: luminosity class is tough!

The discussions with people whose knowledge about physics follows the weaker part of the physics blogosphere but whose self-confidence would suggest that they are Newittons - hybrids of Newton and Witten - often reaches comical proportions.

That was the case of a recent debate with Tommaso Dorigo about luminosity, too. As we mentioned, Tommaso wanted Matt Strassler to admit that experimenters like Dorigo were infallible.

But in the middle of bizarre sociological Dorigo's prayers to the new deity, there was one cute technical comment. For no good reason, Tommaso decided that Matt Strassler's interpretation of the CDF estimate of the cross section for the ghost events - namely 75 pb (picobarns) on page 3 of Matt's paper - is incorrect by a factor of three or so. I suspect that Dorigo just invented this absurd "correction" for the sake of it, in order to undermine Matt's authority a little bit, believing that no one would notice that his "correction" is wrong.

Matt obtained the cross section of the "new", ghost events in the following simple way:

153,895 / (2100/pb) = 73.28 pb

Tommaso Dorigo proposes a different calculation,

153,895 / (742/pb) = 207.4 pb

although he is never quite able to complete this division and announce his - ludicrously high - result. Given the fact that e.g. Giromini et al. predict the cross section to be 50 pb or 35 pb on page 4 for various masses of the Higgs, in a paper that claims to match the data, Dorigo could perhaps find a reason to figure out that 207.4 pb could be too high. But he seems to have no idea about the difference between 75 pb and 200 pb.

Dorigo offers no technical arguments to support his bizarre figures. Instead, he mysteriously tells us that he has talked to the "main author of the CDF study". Well, maybe he should subtly inform her that she is dumb as a door knob, too, if she exists. ;-) On the other hand, Matt includes a very detailed and crystal clear explanation of the way how the cross section - and especially the number of events - was calculated.

Fine: so 742/pb or 2,100/pb?

Of course, the total integrated luminosity, 2,100/pb (two thousand and one hundred inverse picobarns) must be used as the denominator, as Matt Strassler explains in detail, and my task will be to explain this simple fact so that even people like Tommaso Dorigo will understand. It may be a bit like Brian Greene in the TV show, trying to explain Einstein's equations to his dog ;-), but let me try, anyway.

The luminosity is a quantity that determines how many times the initial state of two-particle collisions has been repeated in an experiment. It is expressed as the "number of colliding particle pairs per unit area and per unit time". The more particles you collide each second, the more collisions you will get. The more accurately you focus the beams, the smaller the area becomes and the higher chance of collisions you get. That explains various proportionality laws.

All the areas are usually expressed in barns: one barn is exactly 10^{-28} squared meters, roughly the cross section of a proton. The typical cross sections of new, interesting processes in particle physics are much smaller, e.g. several picobarns: one picobarn is 10^{-40} squared meters.

If you integrate the luminosity over time, you obtain the so-called "integrated luminosity". It is expressed as the "number of colliding particle pairs per unit area". The integrated luminosity has units of inverse area: note that the inverse seconds have disappeared. This quantity is a coefficient that you should multiply by a cross section "sigma" of a given process to predict the dimensionless number of actual events.

The Tevatron, the accelerator at Fermilab, has been colliding protons against antiprotons. So the "total integrated luminosity" refers to the flux of colliding proton-antiproton pairs.

Analogously, the cross sections that should be multiplied by this "total integrated luminosity" to get the number of events are cross sections calculated from proton-antiproton pairs as the initial states. Protons and antiprotons are pretty complicated beasts and the theoretical calculations with proton-antiproton initial states require a lot of dirty QCD technology - like the parton distribution functions. But that's what you have to do if you want to predict how many times the colliding protons and antiprotons produce e.g. a top-quark.

Now, there's no doubt that the total integrated luminosity (of proton-antiproton beams) used to suggest the "lepton jets" in the recent CDF paper is 2,100/pb: see e.g. the second sentence of the abstract. If you want to keep things simple, the right denominator has always been 2,100/pb and there is nothing to talk about. But still, you may ask: why the hell Tommaso Dorigo is talking about 742/pb? Isn't he supposed to know at least some basic things here?

Silicon vertex tracking

So let me explain what the number 742/pb means and why it's wrong to use it as the denominator in the calculation of the "ghost events" cross section. I have spent literally hours, trying to explain it to Tommaso. And I have mostly given up, much like Brian Greene did with his dog. It is probably not possible. But I am almost sure you will get it.

Most of the proton-antiproton collisions are boring. They produce a few jets - streams of strongly interacting particles arising from gluons or light quarks or antiquarks. They must also be correctly described by QCD, and they arguably are, but every sane person believes QCD, anyway. What is interesting and "uncertain" are some events in which heavy particles are almost universally produced in the collisions.

Now, what are the heavy particles that the Tevatron routinely produces? The top quark is the heaviest quark but it is too heavy: the Tevatron doesn't produce too many. The generic heavy particles produced by such colliders include the other heavy quarks, bottom and, to a lesser extent, charm. They are referred to as the "heavy flavors".

Can you select the events in which the bottom quarks were created? Yes, you can and you should. A few years ago, they built the silicon vertex tracker (SVT).

It is a small specialized "computer" that takes the data from the silicon vertex detector (SVXII) and the central outer tracker (COT). The gadget quickly reconstructs the tracks and if it finds sufficiently unambiguous evidence that the bottom quarks appeared in the collision area, right after the collision, it tells the system that the event was interesting - at least for the people who study B-physics (of bottom quarks), e.g. in the context of CP-violation (that requires three generations, including the third one with the bottom quark).

Now, only a subset of the events are picked by the strict SVT criteria: the jets in these events are said to be "b-tagged". The precise percentage depends on how strict criteria the SVT adopts: it is partly a matter of conventions. In reality, about 24.4% of the events that excite the dimuon triggers also pass the strict SVT filter: this percentage is referred to as the "efficiency" of the (heavy flavor) QCD events. The silicon vertex tracker may also choose the events "loosely"; in that case, the efficiency jumps to 88% or so. However, if you assume that there is no new physics, pretty much all events in which the dimuon trigger "clicks" should be caused by heavy flavors - essentially by the bottom-antibottom initial states.

In these most special 24.4% events, bottom-antibottom pairs "almost certainly" appear at the very beginning. So at the very beginning, it looks like you just collided bottom-antibottom pairs instead of proton-antiproton pairs. If you now interpret the Tevatron as a machine where you effectively collide bottom-antibottom pairs, it has a smaller luminosity because only a small portion of the proton-antiproton collisions included protons and antiprotons that were "ready to make heavy flavor collisions". Even though the remaining 75.6% dimuon events probably also contained bottom quarks, you discard the collisions as inconclusive.

You may define the corresponding fraction of all the events and normalize it in the same way as you would do with bottom-antibottom collisions. Assuming that the bottom quarks are there whenever the SVT says "Yes", the integrated luminosity of this subset is just 742/pb, not 2,100/pb. The collisions up to this day that have passed the intermediate, loose SVX filter, give you the integrated luminosity of 1,426/pb or so.

So is it OK for someone to write 742/pb in the denominator when he calculates the cross section of the "lepton jets" ghost events? The answer is, of course, No. It's because these "new" events are actually argued not to include bottom quarks as the initial states. For example, Giromino et al. claim that the Higgs is produced and subsequently decays to various h1, h2, and/or h3 pairs (and 16 tau's at the very end). Nima and Neal use various supersymmetric particles instead. So you can't normalize the initial states with the assumption that the bottom quarks are there in the initial states because they are not there.

If the "ghost events" show any new physics or new particles, they are of a very different type than the events okayed by the SVT tracker: let me emphasize that the "ghost events" are okayed by the dimuon triggers only, not by the SVT tracker.

The tight SVT efficiency is 24.4% for the heavy flavor QCD processes but it is close to 0.0% for the ghost events! In that case, it is a childish mistake to clump these two different sets together because the initial states are very different. There are no bottom-antibottom pairs in the initial states of these "ghost events" so you can't simplify the calculation by assuming that they have bottom-antibottom initial states. Instead, you must return to the collisions of protons and antiprotons, unconstrained by any SVX filters, to use the luminosity of proton-antiproton pairs, and to calculate the corresponding cross sections from proton-antiproton initial states.

The relevant integrated luminosity is 2,100/pb and because it is pretty high, the calculated cross sections will be deservedly low. Let me summarize the integrated luminosities:

• 2,100/pb: all, SVX-unfiltered events; a small part (743,006) were dimuon events; the number 153,895 or so ghost events among them was reconstructed
• 1,426/pb: the loosely SVX-filtered events; a small part (590,970) were dimuon events; the number 72,553 or so of ghost events among them was reconstructed
• 742/pb: the tightly SVX-filtered events; a small part (143,743) were dimuon events; none of them (0) was a ghost event but the detailed composition of the QCD events is known and important
  

Tables

There's one more simple, graphical way to see that the 153,895 events were (and had to be) chosen from the broader 2100/pb sample and not from the 742/pb sample and that the interpretation of the numbers in this list above is correct.

Open the CDF paper on page 16. The set of all dimuon events - 743,006 - is divided to the 589,111 QCD events and our 153,895 ghost events. In the second column of this Table II, you see that only 143,743 events passed the tight SVX filter, neither of which was a ghost event.

Now, if you switch to page 12 and look at Table I, you may add the entries to get 143,000+ and to see that exactly these tight SVX-positive events correspond to the (smaller) integrated luminosity of 742/pb, as the caption of Table I says. For another "written proof" that the 742/pb luminosity corresponds to tightly SVX-filtered collisions, and not all (unfiltered) collisions as Tommaso seems to think, see page 11/52 of Giromini's talk.

In other words, among the 742/pb events (those that passed the tight SVX filter), none of them was a ghost event. You must go to the larger set of all 2100/pb events - unconstrained by any SVX filters - to "see" any ghost events, and their actual number still remains questionable, as Matt argues.

Incidentally, if you only picked the loosely SVX-filtered events, you would get exactly 590,970 events (Table II), roughly 518,417 of which would be heavy flavor QCD events. The remaining 72,553 or so ghost events that passed the loose SVX filter would give you an estimated 72,553 / (1426/pb) = 51 pb cross section for the ghost events, less than 75 pb in the unconstrained ensemble: 1,426/pb is the estimated luminosity after the loose SVX filter. Once again, among the tightly SVX constrained events, your calculated cross section for the ghost events would be 0 pb because the tight SVX constraint doesn't allow the muons to get too far.

If you analyze how various numbers above were determined, you will find out that the number of all dimuon QCD events, 589,111, was actually not directly measured but calculated from the measured number of 143,743 tightly SVX-filtered events, by dividing the latter number by the 24.4% efficiency (by 0.244) that was determined otherwise.

Analogously, the approximately 153,895 ghost events are calculated as the difference of all exactly 743,006 events (which were actually seen) minus all the approximately 589,111 QCD events (whose number was calculated from the efficiency and from the number of tightly SVX-filtered events). However, both of these calculated numbers, 589,111 and 153,895, are subsets of the set of 743,006 events that correspond to the SVX-unconstrained sample whose integrated luminosity is 2100/pb. The sizes of the subsets of all the 743,006 events are calculated from the detailed knowledge of the tightly SVX-filtered events (by a method that Matt has explained, too) but these calculated events are not SVX-filtered themselves: only 143,743 (exactly) events were tightly SVX-filtered.

This key difference between "events actually belonging to an ensemble E742" and "events belonging to a larger ensemble E2100 whose number is not directly measured but rather calculated by looking at a smaller ensemble E742" is another point that has probably confused Tommaso Dorigo profoundly and hopelessly. At any rate, there were dozens of other ways for him to see that his conclusion was wrong. He wasn't able to realize either of them.

The moral of the story

So, a recommendation for Tommaso Dorigo: don't ever try to ignore comments of people like Matt Strassler and their understanding of physics and your papers. Thank me. You're welcome. ;-)

And yes, I think that you should be kind of mildly punished for deliberately directing the anonymous hostile people who read your blog against me in his "appetizer". It's not my fault that you have demonstrated your incompetence. You began these silly attacks of yours and you politely asked me to explain you how Matt calculated those 75 pb which you couldn't possibly get. So I did so. Is that a crime? But you collaborated on it!

Everyone who knows me knows that I love tigers and other animals to live in peace in the dens as well as the holes that you prefer, Tommaso. ;-)

Update

Other members of CDF have sent me the information that indicates that they really meant that the cross section of the new events was above 200 pb i.e. 153,895 ghost events all came from 742/pb. Because the main discussion with Tommaso was about the proposition that they meant, not about the real cross section and not about the natural interpretation of the paper, I gave Tommaso the apology he wanted.

Such a statement of CDF about unexplained events is 3 times more unusual than the already-unusual previous statement and I feel that the paper was written in a confusing way deliberately so that the full craziness of the main statement remains fuzzy not only for the theorists who read about 1/2 of the paper but even for some CDF members.

Mikhail Lomonosov: a birthday

Mikhail Lomonosov was born to a fisherman at an Arctic Russian island on November 19th, 1711, i.e. 297 years ago (according to the new calendar).

On the picture, he may look like a French nobleman but that's how peasants looked like in the Russian Empire - after some successful life. The people who despise the Russian Empire are surely deluded. Lomonosov was a remarkable poet and polymath. He died in 1765.

A curious kid

Mikhail's thirst for knowledge was unlimited so he decided to walk to Moscow: notice that Russia is a pretty big country. He lived from 3 kopecks a day - something like 3 U.S. cents a day - but his progress was stunning. In 5 years, he completed a 12-year course and he was the best guy in his class.

After a year in Kiev, he returned to Moscow and then he went to Saint Petersburg. Those guys sent him to Germany. He learned French and German and imitated German poets, establishing the modern Russian literary language along the way. The Russian scholarship was not enough to live in Germany well so - together with his new wife - he returned to Russia.

After having been a chemistry professor and the university president in Petersburg, he founded the State University in Moscow (together with Ivan Shuvalov, his patron). These days, it is the largest Russian university and it is named after him (much like the Lomonosov Ridge in the Arctic Ocean).

He also revived the art of mosaics. The Battle of Poltava (in 1709, where Peter I humiliated Sweden) on the left side is his most sophisticated piece. In letters to Leonhard Euler, he explained that he was led to this art by chemical experiments with minerals. ;-)

Now, you shouldn't doubt that he also wrote The History of Russia, The Russian Grammar, established his own style of poems, and attempted to write an epic about Peter the Great. But let us quickly switch to another discipline that showed his remarkable versatility:

Science

As a physicist, he made some experiments leading him to the importance of the mass conservation law. I can't quite believe that it was such a new insight at that time but Euler had to read about this stuff all the time. ;-)

Related experiments convinced him that the commonly accepted phlogiston theory - presenting heat as a material - was rubbish. The mass of the metals didn't change and Lomonosov thus concluded that "Robert Boyle was deluded". ;-) Of course, when you want to be really accurate, the heat has a nonzero mass, m=E/c^2, but it was clearly too small to be measured by him.

So Lomonosov in fact did consider heat to be a form of motion. These changes of the paradigm were important for the later formulation of the kinetic theory of gases and statistical physics in general. The role of people like Lomonosov is often underestimated. He was convinced that light was made out of waves, too. His intuition (or just good luck?) that led him to choose the "better" theories of pretty much everything looks remarkable to me.

His Northern origin helped him to become the first person to see frozen mercury (around -40 degrees: it doesn't matter whether you like Celsius or Fahrenheit degrees in this case).

As far as the planets go, you might think that Mercury has made him famous, too. You would be slightly wrong but you would be close to the truth: Lomonosov was the first man to argue that Venus had an atmosphere. He believed in some kind of evolution which allowed him to demonstrate the organic origin of soil, peat, coal, petroleum, and amber. He published a catalog of 3,000 minerals and explained the formation of icebergs.

Geology

He was an extraordinary geographer (and a geologist!), too. Lomonosov theoretically predicted the existence of Antarctica, by looking at the size and features of the Southern icebergs. He was right once again. He improved the methods of navigation and even organized a 1764 expedition to find the Northeast Passage (from the Atlantic to the Pacific Ocean, via the Russian North).

The most impressive achievement seems to be his incomplete theory of continental drift: he mentioned the moving continents in his book, "On Earth's Layers". He was very close to this theory 200 years before it was accepted. Even though Lomonosov didn't like to paint himself as an exceptionally deep and mysterious philosopher, as a polymath, he was probably more often right about things than e.g. Gottfried Leibniz. Nevertheless, his fame in the Western world remained infinitesimal and it is infinitesimal even today.

Parallel Universes and science on TV

The History Channel has aired

Parallel Universes

and one of the stars of the show, Clifford Johnson, seems to be unhappy about the outcome.

The idea of the program is that the newest results in science indicate that our Universe is probably much larger than we thought and it can contain many regions that are not smoothly connected to ours but that are qualitatively similar, the parallel universes. And the filmmakers thought it was a great theme for a TV program. And in fact, so do I. But...

What do these parallel universes mean?

Let me begin with the term "parallel universes". It is a term that seems to be exciting for a certain large group of the laymen (and filmmakers) although it creates almost no excitement among most professional physicists. The phrase has been given at least three vastly different meanings:

1. different histories that could occur in quantum mechanics interpreted with the many-worlds interpretation
   
2. different stringy vacua that may or may not be connected with ours by bubble nucleation within eternal inflation
3. different branes that may be parallel to our, Standard Model brane in our world if it is a braneworld

Again, professionals would never confuse these three concepts but the laymen and filmmakers often do - because what they really understand about these concepts are just the two words, "parallel universes". With this poor resolution of their wavelets, the very different concepts above may coincide.

However, the "parallel universes" in the many-worlds interpretation of quantum mechanics do not change any observation we could ever do, at least in principle. In the many-worlds interpretation of quantum mechanics, there exists a whole tree of alternative worlds where the past events took place with different outcomes. Our "branch" of the tree was chosen randomly. But we can't have any contact with the other branches where the history differs. For example, in many "alternative universes", Adolf Hitler may have won the war.

But we will never see these other worlds because the history of our world is something that can never be rewritten again. These different worlds have separated from ours, they will never reunite, and if you wish, you may also decide to believe that the other worlds don't exist (and choose e.g. the Consistent History approach, a fully satisfactory post-Copenhagen interpretation).

Adopting the many-worlds interpretation can't change the morality of rational people, either. While there may exist other worlds where you are a thief, mass murderer, global warming alarmist, or even an aggressive crackpot ;-) and you might think that these other worlds diminish the importance of your decisions, the reality is different. In this world, you will only be judged for the things you have done in this world, not in the others, so the existence of other worlds is inconsequential once again.

Also, the many-worlds interpretation of quantum mechanics was first coined half a century ago. That's surely not a topic that should be discussed as cutting-edge science.

Instead, this program primarily focused on the other two types of "parallel universes" - those from the stringy landscape and the possible parallel branes in our world. In principle, there may exist a causal contact between our world and these "parallel worlds" if the latter exist. But the nature of this contact is very different in both cases. In the case of the different vacua of the string landscape, they might exist within bubbles that emerge somewhere in our Universe and that will expand (or bubbles in a grandson or great grandson universe etc.) or, on the contrary, our Universe might have arisen from a bubble in another one. The causal relationship is very distant and asymmetric.

On the other hand, if there are parallel branes inside our braneworld, they are just a tiny fraction of a millimeter away from us (in the direction of a new coordinate of space). In principle, we can interact with them, at least gravitationally. We could send and receive gravitational waves - and perhaps other signals - to/from this additional brane if it existed and hosted life.

Clifford Johnson says that he has never heard about "level N parallel universes" in the scientific context, where N is an integer. Well, it's time to read one of Max Tegmark's papers, Clifford. ;-)

Are these things exciting?

Now, are these scenarios more likely than they were two decades ago? I think that the answer is clearly Yes. Are they guaranteed to be true? In the case of parallel branes in our world, the answer is No, we don't know how many parallel branes (and hidden gauge groups) there are in our compactification if any; in the case of other compactifications of string theory, the answer is Probably yes, we are almost certain that our type of "vacuum" is not the only vacuum-like solution to the fundamental equations of Nature. Even if you wanted to be extremely speculative and assume that all of string theory is wrong, more general insights have made it unlikely that our vacuum is a completely unique solution to some equations.

But we're not really sure about the existence of any "evolution links" between these other compactifications and our world; we're not sure whether the eternal inflation and other "nonminimal cosmologies" are physically relevant. So we don't know whether the multitude of compactifications has some implications that can influence the lives of the ordinary and even less ordinary people.

But are these notions exciting? Well, in science they are acceptable only if they are compatible with the experiments that have already been done. For example, one easy experiment implies that there are no dinosaurs in your apartment. All theories that would imply that there are easily visible dinosaurs over there are ruled out. There is still room for new phenomena but they are pretty subtle and it's damn hard to discover them. So if someone only gets excited by the dinosaurs in her bedroom or something else of the sort, she will be disappointed!

Now, are the typical viewers of the History Channel excited about the prospect of having an unusual signature at the LHC? What about a newly created particle that decays into many smaller particles isotropically, with apparently thermal distribution? Well, I think that the answer is obviously No, she is not excited. She doesn't even recognize that we have just produced a mini black hole. Even if she were told so, she has no idea whether it should be surprising or not.

Why isn't she excited? Because she doesn't know the things that you need to know to have sensible expectations about these relatively abstract experiments. She's been doing other things in her life. You only absorb the necessary background if you study these and related things at the technical level for years. By definition, the History Channel is not focusing at this expert audience. If it were, it would be the arXiv.TV station, not the History Channel.

Does it mean that non-experts shouldn't be shown any science? I think that the answer is a resounding No. Science on TV is important because it inspires newer generations and because it removes some kind of "unhealthy mystery" from the scientists. People should know that scientists do things that may be fun for many other people and they should know that these mysterious scientists who seem to be decoupled from the "ordinary world" are not conspiring to secretly destroy the world all the time. ;-) However, the TV programs are not focusing on the expert audiences so they have different (lower) technical standards and different (more entertainment-industry-like) criteria.

Still, I think that a good filmmaker of scientific programs should try to understand the topics and should try to be accurate. The accuracy will never be the only benchmark of his or her work but it will be one of them. The accuracy of technical statements that would turn a regular viewer off is almost likely to be sacrificed, to one extent or another. The Big Bang Theory at CBS is an exception: Sheldon Cooper's statements are remarkably accurate and reflect how a very bright and well-informed physicist would genuinely react to various things. The adviser is doing a superb job.

The price that you pay for this accuracy in TBBT is that the audiences can't quite identify themselves with Sheldon. They still (usually) like him but they know that "he's somewhere else" and they are ready to ignore the details of what he says. This decoupling is a price for the accuracy: the experts and the laymen are at a different frequency, indeed, and any TV show that shows them to be at the same frequency is guaranteed to be inaccurate about the science.

By the way, I want to mention a few examples of the better-than expected accuracy of TBBT. For example, Penny said something about "waiting for light years, as you - the physicists - would say". In a generic sitcom that mentions science, the actual "scientists" would think just like Penny does. A "light year" sounds scientific so it should clearly be used by scientists and others who want to sound as scientists.

But in TBBT, Sheldon explains very aptly that a physicist would actually never use the phrase because a "light year" is a unit of distance, not time, and gives a few more examples of a similar confusion.

He also defines astrology very accurately to make it clear why it is a mass delusion and debunks several additional science-loaded myths. Leslie Winkle realistically mentions some would-be predictions (e.g. modifications of dispersion relations) that some of her charlatan colleagues believe to follow from loop quantum gravity. And so on. These technically accurate sentences may only have been accurate because it is OK if the viewers don't quite understand - it's part of their purpose, after all. ;-) These sentences are produced by geeks who are not supposed to be understood.

However, there exists a different kind of statements and messages that the viewers are surely capable to understand and that should be communicated accurately, even in generic TV programs about science: the sociological statements.

The audiences should get a fair picture about the IQ of the people who work on various topics, the degree of respect they enjoy from their colleagues, the amount of time needed to develop and/or learn a scientific theory, and the confidence of various scientists in various basic, comprehensible statements. This is not hard and a distorted picture of these comprehensible points deserves to be called a dishonesty.

What I want to say is that a scientist should probably be tolerant if a TV program presents a technical idea inaccurately or if it makes it more "sexy" than the scientists actually think it is. Maybe it's because the scientist was narrow-minded, after all. Why didn't she think about a parallel world with dinosaurs in her bedroom? Maybe she should have! :-) And most of the simplification is because the normal viewers could simply not swallow the technical stuff in its precise form.

But scientists should expect and demand the accuracy in the filmmakers' description of the sociology of their fields: who believes whom and how much. These points don't have to be quite perfect but they should simply not be entirely wrong.

For example, it would be bad if a program created the impression that all top physicists are thrilled by Max Tegmark's level IV parallel universes. ;-) It would be bad because it is untrue - look at the citation counts - and moreover, even ordinary people are capable to understand that it is untrue. At least, Max Tegmark is a very serious scientist who also likes to write speculative stuff.

There also exist scientists who have never published any valuable stuff and who only create their name by publishing meaningless speculations directed at the laymen, not the peers - and I am talking not only about Lee Smolin - and it would be even worse if a filmmaker were presenting these things as the pillars of contemporary science. That would be as bad as presenting a "consensus" about a man-made climate catastrophe.

But be ready: if you were never imagining a dinosaur living in a parallel universe, it may have been due to your lack of imagination and the filmmaker is likely to be better in this respect, especially because he's been trained and selected to attract wide audiences and many people - and not only ordinary people - are more likely to be thrilled by visually attractive stuff! In fact, I often like visually intriguing stuff, too. It's a different stuff than scientific accuracy but it is another thing that I expect from TV shows that are worth watching.

And that's the memo.

Not Even Wrong and BRST

But let me mention another kind of distortion of science that I find absolutely stunning. Peter Woit, a critic of physics, decided to write a few blog posts trying to (dishonestly) suggest that he has an idea about the contemporary physics research. For no good reason, he chose the BRST quantization, a "modern" technical tool (from the 1970s) to analyze theories with gauge symmetries.

Now, this is a basic stuff that a normal graduate student usually learns when she is first introduced to gauge theories - surely not something that you can publish research papers about. But it is even more funny to look how Peter Woit divided this stuff into parts. In the first part, he talks about the action of symmetries on linear spaces - the material that, I am pretty sure, most string theorists have known since the high school.

Even more interesting is the second part because he effectively copies the section 3.2.1 of "Superstring Theory", a classic 1987 book by Green, Schwarz, and Witten. What Woit says about the BRST issues is more or less correct - it's what Green, Schwarz, and Witten have also written, after all. There are some strange delicate bugs - for example, a real physicist knows that the physically interesting ghost number is often a number different from zero - but most of his comments are OK. Now, isn't it ironic for a vitriolic, Al-Qaeda-style critic of string theory to choose a section of a string theory textbook as a source of explanations of a topic that he views important?

Now, what he is confused by is the philosophy and the very goal of the BRST machinery. The BRST machinery is not really "new physics". It is just a mathematical tool to apply to "old physics" and to determine the right Jacobians whenever gauge symmetries are gauge-fixed, to determine which states are physical, which states are not, and why the unphysical states do not cause any problems. You can use other (less convenient methods) to find the same results - and only the physical results about the physical states are physical (and measurable)! ;-)

Everything else about one's approach to a physical theory - whether we choose a gauge symmetry at all, whether we gauge-fix it now or then, how we gauge-fix it, whether we extend the gauge symmetry to a BRST symmetry, whether we use path integrals or the operator approach etc. - is just a question about our strategy to get the final results (such as the cross sections). We don't construct "new theories" in this way.

And once you learn the definition of the BRST cohomology, you are still light years (or at least years) away from being able to decide about the validity of string theory. These are just entirely different levels of knowledge.

The third and fourth part of Woit's "lectures" are purely mathematical and focus on things like exact sequences. That's perfectly fine but in combination with a grumpy guy who is often quoted as a critic of the abstract mathematical character of string theory that is claimed to be detached from experiments, the focus on the Chevalley-Eilenberg complexes sounds a little bit too ironic, doesn't it? What is the doable experiment that decides whether these complex are relevant for the world around us? Isn't it not even wrong blah blah blah? But none of his anonymous readers - or the journalistic garbage that has promoted the jerk in the media two years ago - cares because all of them are equipped with hypocrisy of an unprecedented degree.

Experimental chauvinism

One more controversy is going to be mentioned here. Matt Strassler published his first analysis of the recent CDF dimuon events paper,

Flesh and blood, or merely ghosts?

As the title indicates, Matt is skeptical about ambitious interpretations of the paper in terms of brand new physics.

Tommaso Dorigo decided to criticize Matt's paper. Tommaso thinks that it was politically incorrect for Matt to

• notice that only a subset of the CDF collaboration signed the paper
• consider the paper to be too short given the importance of the suggested interpretation
• be disappointed that certain extra checks were not performed and certain extra graphs were not included
• be disappointed with some logically questionable interpretations of other graphs.

Tommaso also seems to think that the experimenters themselves are the only ones who have the right to offer an opinion on the reliability of certain results. Recently, I agreed with Tommaso that the papers should be published if they are able to survive a fixed amount of scrutiny, regardless of the "sign" of the papers i.e. whether or not they are surprising for someone.

But I incorrectly thought that the agreement was due to Tommaso's reasonable opinions. In fact, the agreement was a pure coincidence and the reason behind Tommaso's opinions was the dumbest kind of experimental chauvinism you could think of. Tommaso is clearly not alone: other experimenters physically forced Matt to modify some formulations in his paper although - fortunately - the content of the paper hasn't yet been changed.

Now, let me tell you about the actual situation here.

Matt is an exceptional theorist as far as the analysis of raw collider data goes. As a winner of the LHC Olympics, he is probably better in these things than the union of the 370 worst CDF members and at least comparable to the union of the 370 best CDF members. He may lack some particular types of experience but on the other hand, he is clearly more intelligent than virtually all members of the CDF collaboration and the only reason why he didn't become an experimental particle physicist was that he was able to do something more difficult, too.

Which 370 members signed the paper may therefore be a relevant piece of information for a person less qualified than Matt who is deciding whether Matt should be trusted. Unfortunately, the subset is "unknown". ;-)

According to the CDF internal policies, a paper that gets a sufficient number of supporters is published as a paper of the whole CDF collaboration that claims "consensus" in this way. Well, it's questionable whether it is such a good idea to hide who agreed and who disagreed with something but it's their policy. On the other hand, it's just policy, not the truth. And it is only their policy, not an international law.

Theorists like Matt are in no way constrained by similar policies and their task is different from preserving someone's little secrets and taboos and from pretending that they don't know certain things. The theorists' task is to combine all the available information into the most convincing - and therefore hopefully correct - theoretical explanation of the observations.

If an imperfection of the experimenters seems to be a likely explanation - and it is surely a rather important candidate in this case where the alternatives involve a very shocking new type of physics - the theorist must also make reasonable guesses about the likelihood that the experimenters did a certain imperfect step. To make this guess, Matt correctly used all the available information - including the limited number of supporters of the paper - and, as an honest theorist, he also openly revealed all the arguments that have influenced his decisions. The counting of the people was just one of the minor ones.

Tommaso seems to think that it should be a heresy to think that the experimenters are fallible. To make things even more ludicrous, he offers us this nice quote by Freeman Dyson:

The professional duty of a scientist confronted with a new and exciting theory (or data) is to try to prove it wrong. That is the way science works. This is the way science stay honest. Criticism is absolutely necessary to make room for better understanding.

And what is Tommaso's interpretation? Freeman Dyson surely meant that the criticism is only acceptable if it is not directed against the "infallible" Tommaso Dorigo and his friends, Tommaso argues: the criticism must be "constructive". Well, that's an amusing interpretation, especially if Tommaso's idiotic and intimidating attack against Matt's paper is probably supposed to be constructive in this sense. ;-)

Sorry, Tommaso, but Freeman Dyson surely meant what he said: even experimenters are fallible. And some of them are not only fallible but they are as dumb as a door knob if not as Tommaso himself! The history of science is flooded by all kinds of "renowned" experimenters who have proved that relativity was wrong, the Feynman - Gell-Mann V-A theory of weak interactions was wrong, and dozens of other bizarre conclusions.

Whether or not the subgroup of the CDF collaboration discovered something new or important or whether they have just showed their imperfect abilities to manipulate with the detectors and the data remains to be seen. Attempts of hundreds of average experimenters to bully a theorist are surely not helpful in revealing the truth.

The Lizard-Spock Expansion

Watch the newest episode of The Big Bang Theory, 2x08, at

Megavideo (click)

AGW: Jack Schmitt quits The Planetary Society

Harrison Schmitt, an award-winning astronaut and a geologist, has resigned from The Planetary Society.

Letter

He explains that the return to the Moon - where he has been (he speaks about this issue in this lecture since 7:00) - is the most natural path to Mars (and perhaps other bodies). But he also criticizes the TPS statement accelerating research into global climate change through more comprehensive Earth observations:

As a geologist, I love Earth observations. But, it is ridiculous to tie this objective to a "consensus" that humans are causing global warming in when human experience, geologic data and history, and current cooling can argue otherwise. "Consensus", as many have said, merely represents the absence of definitive science. You know as well as I, the "global warming scare" is being used as a political tool to increase government control over American lives, incomes and decision making. It has no place in the Society's activities.

Global warming causes more sex - and hundreds of other things: a film version of this list.

Hat tip: Marc Morano